CHARACTERIZATION OF PENA AND TETM RESISTANCE GENES OF NEISSERIA-GONORRHOEAE ISOLATED IN SOUTHERN AFRICA - EPIDEMIOLOGIC MONITORING AND RESISTANCE DEVELOPMENT

Objective. To investigate penA and tetM resistance gene variation of N eisseria gonorrhoeae in order to define gene types for epidemiological monitoring and resistance development. Design. Isolates of N. gonorrh oeae which were susceptible and resistant to penicillin and/or tetracy cline were selected. Strains comprised South African isolates (22 from Bloemfontein, 13 from Transvaal, 20 from the Cape) and 15 Botswana an d 4 Namibia isolates, The penA genes (2 kb) of all strains and tetM ge nes (765 bp) of 11 high-level tetracycline-resistant strains were ampl ified and restricted with Hpall. Results and conclusions. Twelve diffe rent Hpall fingerprint patterns were obtained from the 74 isolates ana lysed for penicillin-binding protein (PBP) 2 gene (penA) alterations, Focusing on the transpeptidase domain, 25 isolates (3 whole gene patte rns, minimal inhibitory concentrations (MICs) less than or equal to 0, 03 - 0,125 mu g/ml) had restriction sites equivalent to those previous ly described for a susceptible strain, Of the remaining 9 PBP 2 gene g roups, 25 strains fell into a designated group E. Penicillin/penicilli n + clavulanic acid MICs determined on these group E isolates gave a r ange of 0,125 - 2,0 mu g/ml, although MICs against 4 strains were less than or equal to 0,03 mu g/ml, MICs of penicillin/penicillin + clavul anic acid for the 24 isolates that Contained altered PBP 2 transpeptid ase gene regions not designated group E were only less than or equal t o 0,03 - 0,125 mu g/ml, The lack of a Hpall restriction site at nucleo tide 1934 in the PBP 2 gene of group E strains was indicative of a sma ll terminal region of N. cinerea DNA. This gene block, which was found in all the southern African areas studied, appears to predispose isol ates to increased penicillin resistance. The 25,2 MDa conjugative plas mid carrying the tetM resistance determinant was readily demonstrated in 11 Botswana/ Namibia isolates exhibiting high-level resistance to t etracycline (MICs greater than or equal to 16 mu g/ml). The tetM gene was shown to be of the American type.